Tadalafil vs Sildenafil

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For patients dealing with erectile dysfunction (ED), certain drugs that influence the blood flow to pelvic organs can help in restoring and maintaining an erection. Tadalafil and Sildenafil are two such medications typically prescribed for this condition. Both of these work by inhibiting phosphodiesterase type 5 (PDE5), an enzyme found primarily in the vascular smooth muscle of the corpus cavernosum, thus promoting blood flow necessary for achieving an erection. However, they differ slightly in their pharmacodynamics and duration of action. Tadalafil, known under the brand name Cialis among others, has a longer half-life, which allows it to provide therapeutic effects up to 36 hours after dosing; hence its nickname "the weekend pill". On the other hand, Sildenafil or Viagra typically lasts approximately 4-6 hours before its effects start wearing off.

What is Tadalafil?

Tadalafil (the generic name for Cialis) was a significant advancement in the class of drugs known as PDE5 inhibitors, which were developed after the first class of erectile dysfunction drugs. Tadalafil received FDA approval in 2003. This medication works by blocking an enzyme called phosphodiesterase type 5, effectively increasing blood flow to certain parts of the body. It is most commonly prescribed for erectile dysfunction and benign prostatic hyperplasia (enlarged prostate). Tadalafil has a selective influence on PDE5 with only minor effects on other phosphodiesterases, resulting in fewer side effects than other medications that have stronger impacts on these other enzymes. Notably, one feature distinguishing tadalafil from sildenafil (Viagra) is its longer duration of action—up to 36 hours compared to sildenafil's four-to-six-hour window—earning it the nickname "The Weekend Pill."

What conditions is Tadalafil approved to treat?

Tadalafil is approved for the treatment of various conditions, including:

  • Erectile dysfunction (ED) in adult males
  • Benign prostatic hyperplasia (BPH), a non-cancerous enlargement of the prostate gland
  • Pulmonary arterial hypertension (PAH), high blood pressure in lungs' arteries. Sildenafil shares similar approvals but is also specifically authorized to treat altitude sickness.

How does Tadalafil help with these illnesses?

Tadalafil helps to manage erectile dysfunction by increasing the amount of nitric oxide available in the muscles of the penis. It does this by inhibiting an enzyme called phosphodiesterase type 5 (PDE5), which is responsible for breaking down cyclic guanosine monophosphate (cGMP). cGMP is a substance that relaxes and widens blood vessels, thus improving blood flow. Nitric oxide released during sexual stimulation leads to production of cGMP, aiding in achieving and maintaining an erection. By blocking PDE5 from breaking down cGMP, Tadalafil can maintain higher levels of cGMP for longer periods leading to improved erectile function. The main difference between Tadalafil and Sildenafil lies in their duration of action; Tadalafil typically lasts for up to 36 hours while Sildenafil lasts for around four to six hours. Thus patients may choose Tadalafil if they desire a more prolonged effect.

What is Sildenafil?

Sildenafil, better known by its brand name Viagra, is a phosphodiesterase 5 (PDE5) inhibitor used primarily in the treatment of erectile dysfunction. It works by increasing blood flow to the penis during sexual stimulation which results in an erection. Sildenafil was first approved by the FDA in 1998 and has since become one of the most well-known treatments for erectile dysfunction worldwide.

Unlike Tadalafil, another PDE5 inhibitor that lasts up to 36 hours (hence it's nickname 'the weekend pill'), Sildenafil typically begins working within 30 minutes to an hour after ingestion and its effects last approximately four to five hours. This shorter duration makes Sildenafil a suitable choice for individuals who prefer not having medication active in their system for extended periods.

In terms of side effects, compared with SSRIs such as Prozac, sildenafil does not cause weight gain or sexual dysfunction but can cause other side effects like headaches, flushing, indigestion or nasal congestion. The increased blood flow stimulated by Sildenafil can also be beneficial for treating certain types of high blood pressure and heart disease.

What conditions is Sildenafil approved to treat?

Sildenafil is a well-known medication approved by the FDA for the treatment of:

  • Erectile dysfunction (ED), helping to improve sexual performance and satisfaction
  • Pulmonary arterial hypertension, reducing symptoms such as shortness of breath and tiredness

How does Sildenafil help with these illnesses?

Sildenafil is a phosphodiesterase type 5 inhibitor, which functions by promoting the effect of nitric oxide. Nitric oxide plays a crucial role in regulating blood flow to different parts of the body, including sexual organs, thus supporting arousal and performance. Like tadalafil, sildenafil aids erections by increasing blood flow to the penis and decreasing outflow from it when sexually stimulated; however, there are some differences that set sildenafil apart.

One key distinction lies in their duration of action. Sildenafil typically lasts for four to six hours while tadalafil can last up to 36 hours. This makes sildenafil an optimal choice for patients seeking more immediate or short-term effects without having medication active in their system for extended periods. Furthermore, compared with tadalafil's 'once daily' dosing schedule recommendation due to its long half-life, sildenafil offers flexible dosing (as needed), allowing patients more control over usage based on planned sexual activity rather than adhering strictly to a daily intake regimen.

How effective are both Tadalafil and Sildenafil?

Both tadalafil (Cialis) and sildenafil (Viagra) have established histories of success in treating patients with erectile dysfunction, and were approved by the FDA a few years apart; sildenafil in 1998 and tadalafil in 2003. These medications work similarly as they both belong to a class of drugs known as phosphodiesterase-5 inhibitors that enhance the effect of nitric oxide, which is responsible for relaxing muscles in the penis and increasing blood flow.

A direct comparison study published in 2005 demonstrated similar efficacy between tadalafil and sildenafil. In this double-blind trial, both drugs showed comparable effectiveness at improving sexual function scores based on standard questionnaires used to evaluate erectile dysfunction treatment outcomes. However, there are differences regarding onset time and duration of action: while sildenafil starts working within about an hour after ingestion with effects lasting up to five hours, tadalafil tends to start working more slowly but remains active for up to 36 hours.

In terms of safety profiles, side effects associated with these medications are typically mild-to-moderate such as headaches or facial flushing due to increased blood flow. Both show similar tolerability though some studies suggest that fewer visual disturbances occur with tadalafil use compared to sildenafil.

Given their successful track records along with their unique pharmacokinetic properties - rapid onset for sildenafil versus extended duration for tadalafil - choosing between them often comes down individual patient preferences or specific circumstances.

abstract image of a researcher studying a bottle of drug.

At what dose is Tadalafil typically prescribed?

Oral dosages of Tadalafil range from 2.5–20 mg/day, but studies have indicated that 10 mg/day is sufficient for treating erectile dysfunction in most people. It can be taken as needed or on a daily basis. The dosage can be increased to 20 mg or reduced to 5 mg based upon the individual’s tolerability and efficacy response. For daily use, the recommended dose is 2.5mg once a day, which may increase to 5mg per day based on personal tolerance and effectiveness.

Sildenafil's standard starting dose is typically either 50mg or 100mg taken as needed approximately one hour before sexual activity but no more than once daily. In some cases, depending on tolerance and effectiveness, doses could be reduced to as low as 25mg or upped to a maximum recommended dosage of 100mg per day.

At what dose is Sildenafil typically prescribed?

Sildenafil treatment is typically initiated at a dose of 50 mg, taken as needed approximately one hour before sexual activity. Based on effectiveness and tolerability, the dose may be increased to a maximum recommended dose of 100 mg or decreased to 25 mg. It's worth noting that sildenafil is not meant for continuous daily usage; it should only be used when sexual activity is anticipated. The maximum dosing frequency is once per day, and exceeding this limit could potentially lead to an increase in side effects such as flushing, headache or changes in vision. So remember: start with an initial dose of 50mg then adjust based on your body's response and always adhere strictly to the dosage instructions provided by your healthcare provider.

What are the most common side effects for Tadalafil?

The most common side effects of tadalafil and sildenafil are similar, although there may be some differences in frequency or severity. Both medications might cause:

  • Headache
  • Upset stomach or indigestion
  • Diarrhea
  • Flushing (warmth, redness, or tingly feeling)
  • Nasal congestion
  • Back pain (more common with Tadalafil)
  • Muscle pain or weakness
  • Nausea, dizziness
  • Abnormal vision (changes in color vision, blurred vision)
  • Rash or skin flushing -Sleepiness/drowsiness

Both drugs can also lead to a rare but serious side effect called priapism - an erection that won't go away. If you experience this symptom for more than four hours, seek immediate medical attention as it could cause permanent damage to the penis.

Always consult your healthcare provider before starting any new medication.

abstract image of a patient experiencing side effect

Are there any potential serious side effects for Tadalafil?

While both Tadalafil and Sildenafil are generally safe, they can in rare cases lead to serious side effects. Be alert for:

  • Signs of an allergic reaction: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, or trouble breathing
  • Vision changes: sudden decreased vision, including permanent blindness in one or both eyes; blurred vision; sensitivity to light; color perception changes
  • Priapism: A painful erection lasting more than four hours due to increased blood flow. This is a medical emergency that could potentially result in damaged penile tissue.
  • Hearing problems: sudden decrease or loss of hearing, ringing/tinnitus in ears
  • Heart symptoms: chest/jaw/left arm pain, nausea/nausea during sexual activity, fainting and severe dizziness. If you experience any such adverse effects after taking either Tadalafil or Sildenafil contact your healthcare provider immediately.

What are the most common side effects for Sildenafil?

Sildenafil, often used for erectile dysfunction and pulmonary arterial hypertension, can cause several side effects which include:

  • Headaches or migraines
  • Flushing of the face
  • Upset stomach or indigestion
  • Vision problems such as blurred vision or increased sensitivity to light
  • Dizziness or lightheadedness
  • Stuffy nose
  • Insomnia (trouble sleeping)
  • Muscle pain or backache It's important to note that these are potential side effects and not everyone who uses Sildenafil will experience them. If you do encounter any severe reactions, it is strongly advised to contact your healthcare provider immediately.

Are there any potential serious side effects for Sildenafil?

While Sildenafil is generally well-tolerated, there are potential side effects to look out for. These may include:

  • Signs of an allergic reaction: hives; difficulty breathing; swelling in your face, lips, tongue or throat.
  • Severe vision changes or sudden vision loss
  • Ringing in your ears or sudden hearing loss
  • Irregular heartbeat and chest pain
  • Shortness of breath
  • Swelling in hands, ankles, feet (edema)
  • Lightheadedness that can lead to fainting
  • An erection painful or lasts longer than 4 hours

If you experience any of these symptoms while using Sildenafil, it's important to stop taking the medication and seek immediate medical attention.

Contraindications for Tadalafil and Sildenafil?

Both Tadalafil and Sildenafil, like most other erectile dysfunction medications, may cause certain side effects in some individuals. If you experience any serious adverse reactions such as prolonged or painful erections lasting more than 4 hours, sudden vision loss in one or both eyes (a sign of non-arteritic anterior ischemic optic neuropathy - NAION), or sudden hearing decrease or loss while taking these medications, please seek immediate medical attention.

Neither Tadalafil nor Sildenafil should be taken if you are currently on nitrates (commonly prescribed for chest pain), as this can lead to a dangerous drop in blood pressure. Always inform your healthcare provider about all the medicines that you take; nitrate drugs will need to be stopped before starting either tadalafil or sildenafil treatment to avoid hazardous interactions.

Additionally, remember that both Tadalafil and Sildenafil could potentially interact with numerous other substances including certain antibiotics and antifungals, high blood pressure medications, HIV protease inhibitors among others. Therefore it is vital to always keep your physician informed about all medication you're taking including over-the-counter drugs and supplements.

How much do Tadalafil and Sildenafil cost?

For the brand name versions of these erectile dysfunction treatments:

  • The cost for 10 tablets of Cialis (tadalafil, 20 mg) averages around $450–$500. This works out to be about $45–50 per use, as it is usually taken on an as-needed basis.
  • Viagra (sildenafil, 100 mg), on the other hand, costs about $600 for a pack of 10 tablets. This amounts to approximately $60 per use.

Thus if you're taking both medications at their highest dosages and prices into account only, brand-name tadalafil is less expensive than sildenafil. However, remember that price should not be your primary consideration when deciding which drug fits your personal needs better.

In terms of generic versions:

  • Tadalafil (20 mg tablets) can come in packs from 2 up to several dozens with approximate costs starting from around $3-$5 per tablet.
  • Sildenafil is available in similar quantities with prices beginning at roughly $1-$2 per tablet.

Again note that cost can vary significantly based on location and pharmacy chosen.

Popularity of Tadalafil and Sildenafil

Tadalafil and sildenafil are both widely used to treat erectile dysfunction (ED) and pulmonary arterial hypertension.

In 2020, Tadalafil, also known under the brand name Cialis, was prescribed to approximately 8 million people in the US. It accounts for about 30% of PDE5 inhibitor prescriptions in the country. One significant advantage of tadalafil over other ED medications is its long duration of action - up to 36 hours.

Sildenafil, more commonly known as Viagra, was prescribed to around 12 million men in the USA during that same year. In terms of prescriptions for PDE5 inhibitors specifically intended for erectile dysfunction treatment in America, sildenafil holds a dominant position with roughly a little over half (50-55%) market share. Sildenafil's popularity has been relatively steady over recent years due largely to its established reputation since it was first introduced back in late nineties.


Both Tadalafil (Cialis) and Sildenafil (Viagra) have established histories of use in treating erectile dysfunction, supported by numerous clinical studies that demonstrate their effectiveness over placebo. Both belong to a class of drugs known as PDE5 inhibitors and work similarly by increasing blood flow to the penis during sexual stimulation. However, they differ in terms of onset, duration of action, and how food intake affects their absorption.

Tadalafil usually starts working within 30 minutes to two hours after consumption and its effects can last up to 36 hours. This longer duration makes it a good option for men who want more spontaneity rather than pre-planning intercourse. On the other hand, sildenafil typically takes effect within 30 minutes but lasts only about four hours.

Both medications are available in generic form which allows for significant cost savings especially if out-of-pocket payment is required. It's worth noting that while both drugs show high efficacy rates, individual response varies so an adjustment period might be needed before noticeable results are seen.

Side effects between the two drugs are similar with most common ones being headache, flushing or redness on face/chest area, stuffy nose or indigestion; however these side effects tend to be mild and temporary. Patients should immediately seek medical help if they experience sudden vision loss or an erection lasting more than four hours.